This is paraphrased from his book, "Forgotten God":
"The Holy Spirit is God, within us. When Jesus came to the disciples and told them He was going to leave them, He assured them it was better that He leave, and The Holy Spirit take His place. If you asked someone who they'd rather have in front of them; Jesus, who they can touch and speak to in person, or the invisible Holy Spirit, people would most likely choose Jesus. The amazing thing about The Holy Spirit is that Jesus Himself tells the disciples they should consider it their advantage, The Holy Spirit take His place.
If we truly believe The Holy Spirit is in us, we should act like it. If we have The Holy Spirit living in us, our lives should reflect it. If I told you I had this power dwelling within me that made me an amazing basketball player and I was awful at basketball, you wouldn't believe me. The same is true with The Holy Spirit. If we have this amazing God living in our hearts but we don't live out lives that reflect Him, what are we doing? Who are we fooling?"
I loved the entire book, and that section of it specifically. No one would ever say, "Justin is an amazing basketball player." It's always been the one sport I've been terrible at (I'm 5'9"). That's a given. I would however, love for people to say, "Wow, Justin really is living a life that reflects the love, grace, and justice of God." If we are living lives that reflect God's heart, people are bound to say things like this about us. Think about the people in your life, living after God's heart. Hopefully you can think of a few people you'd say something like that, about.
I want to end this post with a question you should ask yourself, "What are people saying about God because of me?"